장력 조절 가이드: 테이프의 쭈글거림 및 주름 발생 방지

Telescoping and wrinkling are the two most persistent defects in carrier tape winding. Telescoping manifests as lateral displacement of tape layers, producing a stepped or cone-shaped roll edge. Wrinkling appears as radial or diagonal creases that distort pocket geometry and interfere with cover tape sealing. Both defects share a common origin: an imbalance in the internal stress distribution within the wound roll.

For manufacturers producing carrier tape on high-speed forming equipment, understanding the relationship between winding tension and roll quality is essential. The tension settings that optimize production speed may produce rolls that deform during storage or fail at the feeder.

The Mechanics of Roll Defect Formation

Telescoping

Telescoping occurs when radial compressive stress within the roll exceeds the friction force between adjacent tape layers . Each layer of tape exerts pressure on the layers beneath it as tension is applied during winding. When this pressure exceeds the interlayer friction threshold, layers slide laterally. The cumulative effect produces the characteristic stepped edge.

The friction condition depends on two variables: the radial stress at each interface and the coefficient of friction between tape surfaces. Carrier tape typically presents a smooth, low-friction surface on at least one side, reducing the interlayer friction available to resist slippage.

주름

Wrinkling results from excessive tangential stress in the winding direction combined with insufficient radial support . When a tape layer is stretched during winding, it attempts to contract once tension is released. If the underlying layers cannot accommodate this contraction, compressive forces develop in the radial direction, causing the tape to buckle. The buckle propagates as a wrinkle.

A related defect is the “star defect,” where wrinkles radiate from the core like spokes. This pattern indicates that the tension profile is incorrect in the critical early layers of the roll, where radial stress builds most rapidly .

Why Constant Tension Is Insufficient

The traditional approach to winding tension—maintaining a fixed tension value throughout the roll—creates a predictable stress gradient. As roll diameter increases, each new layer adds compressive load to the layers beneath. If tension remains constant, the innermost layers experience progressively higher compression as winding proceeds.

Research on wound roll mechanics has demonstrated that constant tension winding is a primary cause of both wrinkling and telescoping defects . The radial stress distribution becomes increasingly non-uniform, with the core-adjacent layers subjected to the highest compressive loads. This condition promotes telescoping at the roll edges and wrinkling in the outer layers.

Taper Tension: The Engineering Solution

The standard approach to controlling roll stress distribution is taper tension—a winding profile in which tension decreases as the roll diameter increases. The underlying principle is that as the roll grows, each layer’s contribution to radial stress at the core should be reduced to maintain a uniform or near-uniform stress distribution.

Research on optimum winding tension has applied modified Hakiel models incorporating air entrainment effects to analyze in-roll stress distributions in both radial and tangential directions . These studies demonstrate that winding tension should be gradually changed in the radial direction to minimize tangential stresses while maintaining non-negative radial stress conditions.

The key constraint is preventing the radial stress from becoming negative at any interface. Negative radial stress indicates that the layers are separating, which immediately triggers telescoping since friction force drops to zero. The optimization therefore operates within a narrow window: tension high enough to maintain positive radial stress, but low enough to prevent excessive tangential stress that causes wrinkling.

Taper Tension Profiles

A practical taper tension profile typically begins with a higher tension at the core and decreases progressively as the roll builds. The rate of decrease depends on material properties, tape width, and roll diameter. For carrier tape formed from PC or PS base film, the tension decay rate requires careful calibration because these materials exhibit different elastic recovery characteristics.

One patented winding method for tape-like laminated films specifies a tension change rate of 0% to +0.10% per meter of wound length . Notably, this approach increases tension as winding proceeds—the opposite of conventional taper tension—to prevent roll collapse during transport and storage. The inventors found that negative change rates (decreasing tension) produced stable rolls immediately after winding but resulted in roll deformation during subsequent handling .

This apparent contradiction highlights an important distinction: the optimal tension profile depends not only on preventing defects during winding, but also on maintaining roll integrity through storage and transport. Carrier tape rolls may experience significant temperature and humidity variation between production and end use.

Practical Implementation on Carrier Tape Forming Equipment

Jinyingteng’s roller-type carrier tape forming equipment incorporates tension control at multiple stages: material feed, forming, punching, and final reeling. The reeling section addresses telescoping and wrinkling through several design features.

Independent tension control. Each reeling station operates with its own tension regulation, allowing different lanes to accommodate material variations without compromising the entire roll. The system uses a dual-step mechanism with pneumatic shaft and tension adjustment, with weight markings on the swing arm for repeatable manual calibration.

Single-origin calibration. When switching between reel widths, operators set the width through the interface rather than performing mechanical recalibration. The system allows independent programming of reel gap, tape overlap distance, and the angle at which the tape reverses direction at the reel edge. These parameters directly influence the stress distribution at the roll edge, where telescoping typically begins.

Tension profiling capability. The control system supports winding tension profiles that can be adjusted as a function of roll diameter or wound length. For specific material and width combinations, the tension decay rate can be tuned to match the material’s stress relaxation behavior.

Material Factors in Tension Control

The material behavior of carrier tape base film significantly influences the winding tension window.

Polycarbonate film exhibits lower thermal shrinkage than polystyrene—typically less than 0.1% after 24 hours at 85°C compared with up to 0.5% for PS under equivalent conditions. This dimensional stability translates to more predictable stress relaxation in the wound roll. Tension profiles calibrated for PC tape may require adjustment when running PS, which has greater tendency to deform under sustained compressive load.

Base film thickness also affects the required tension. Thicker films distribute compressive stress over a larger cross-sectional area, potentially tolerating higher winding tension before wrinkling occurs. However, the same thickness increases the radial stress contribution per layer, which may accelerate the onset of telescoping.

Environmental conditions during winding—particularly temperature and humidity—influence both the friction coefficient between tape layers and the viscoelastic properties of the base film. The enclosed material feed section on Jinyingteng’s forming equipment helps stabilize these conditions before tape reaches the reeling stage.

Detection and Correction

Early detection of tension-related defects prevents defective rolls from reaching downstream processes. Visual indicators include:

• Edge profile: A uniform, flat edge indicates balanced stress distribution. A curved or stepped edge suggests telescoping is developing.
• Surface topography: Radial creases or star patterns indicate tangential stress excess. These defects often become more pronounced after the roll relaxes.
• Core compression: The core may indicate excessive tension if it shows deformation or compression marks, particularly with cardboard cores .

When defects appear, the tension profile requires adjustment. Increasing tension reduces telescoping risk by maintaining positive radial stress, but increases wrinkling risk. Decreasing tension has the opposite effect. The optimal setting is the narrow band between these failure modes.

결론

Tension control for carrier tape winding is a balance between two opposing failure mechanisms. Telescoping is prevented by maintaining sufficient radial stress to generate interlayer friction. Wrinkling is prevented by limiting tangential stress that causes layer buckling. The narrow operating window requires tension profiles that account for roll diameter, material properties, and environmental conditions.

Jinyingteng’s carrier tape forming equipment provides the independent tension control and profiling capability necessary to achieve this balance. For SMT manufacturers and component packaging operations, the result is carrier tape rolls that maintain dimensional integrity from production through feeder pickup—reducing stoppages and improving placement yield.